Molded articles may be formed when a preform of an article is placed in a mold for shaping. Removal of the article from the mold after a forming operation is complete without causing damage to the molded article is often carried out as a separate operation during the manufacturing process. Depending on the shape, placement and orientation of various physical features of the molded article, the removal of the article form the mold may require special care to avoid tearing, breakage, or other damage.
In the field of tire manufacturing, a common molding operation includes vulcanizing a rubber composite material in a curing press. Curing presses include molds that enclose a rubber composite preform to provide pressure and heat cures the preform into a useable article, for example, a strip or belt of tire tread. Such tire treads are typically used in tire retreading and other applications.
A typical curing press mold includes a mold plate that forms a cavity. One side of the cavity forms various depressions and ridges that correspond to the desired tread pattern of the tire tread that will emerge therefrom. A plate or platen is placed over the mold cavity after a tread preform has been loaded into the cavity. Pressure and heat are provided by the press to force the preform to assume the shape of the mold cavity and to cure the preform into vulcanized rubber.
In certain tread patterns such as those used for trucks or off-road applications, the tread lugs may have a substantial height relative to the overall thickness of the tread, the tread sipes may be closely spaced, the lugs may have negative draft angles, and other features that can create challenges when prying the finished tread from the mold. Given that rubber is an inherently elastic material, simply pulling one end of the finished tire tread to remove the tread from the mold may present various challenges, including stretching of the tread, tearing or cracking of the tread, and other effects.